150 THE EXCITATION OF AMOEBOID MOVEMENTS 



and retract their pseudopodia aimlessly. Quinine 

 hydrochloride excites them fairly markedly ; and it 

 must be noted that the statement has been made by 

 other authors that quinine stops diapedesis. We have 

 made a hanging drop preparation 1 with a jelly-film 

 in such a way that the cells are not pinned down by 

 the cover-glass, but still absorb atropine, and they 

 therefore were in a position to move about if they 

 wished to. They remained in their original positions, 

 however, and seemed to be content to extrude and 

 retract their "feelers." 



Experiments were made to see if this excitation 

 was due to any chemotactic influence of the alkaloids. 

 Two jellies were made, one of which contained atropine 

 and the other none; and they were so mixed on a 

 slide that there was atropine in one part of the film 

 and not in another. Some citrated blood was placed 

 over the line of demarcation to see if the cells neces- 

 sarily extruded their pseudopodia in the direction of 

 the concentrated alkaloid. They did not do so, how- 

 ever, for, provided a cell absorbed the alkaloid suffi- 

 ciently, the extrusions were made in all directions as 

 usual. 



In order to try to find out whether this excitation 



/ 



increased the ingestion of bacteria by leucocytes, a 

 sample of fresh blood was mixed with a volume of 

 citrate solution and atropine, which contained bacteria 

 in suspension. Having been incubated for some 

 minutes, the cells were spread on jelly; but when 



1 This method will be found in the Appendix, where also another method 

 of preparing kinetic jelly will be found. 



